Huh ? This doesn't make sense....you say they grade objectively but then say they rely on "Ebay and discount sites" ? I don't think that sales on Ebay are "discounted" FWIW. And I am pretty sure that the grades that PCGS and NGC give out have nothing to do with Ebay completed sales or other sales. No, it doesn't help. You basically are saying that PCGS and NGC and the TPGs rely on Ebay for their grading, market or whatever. I doubt they check Ebay for ANY sales info....I doubt they even check Heritage or Stacks while grading, though they MIGHT be aware of a big jump in price at certain inflection points.